JPH06253317A - Color image processor - Google Patents

Abstract

PURPOSE:To provide a color image processor which accurately extracts a target pixel even if conditions change owing to an external factor. CONSTITUTION:An image pickup device 1 converts incident light from a specific image pickup area into a color signal of a reference color among R, G, and B. A comparison part 21 extracts pixels in a density range set by a threshold value setting part 24 among pixels in an object area specified by an object area specification part 22. A monitor area is set as part of the image pickup area of the image pickup device 1 and a correction quantity arithmetic part 34 finds differences between the density of each pixel in the monitor area and reference density set by a reference density setting part 33 by the respective reference colors. The quantity of light incident on the image pickup device 1 is controlled by controlling a light quantity control part 2 so that the differences decrease.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image processing apparatus for extracting pixels within a predetermined density range for each reference color with respect to a predetermined target area set in an image picked up by an image pickup means. Is.

[0002]

2. Description of the Related Art Conventionally, an image pickup device such as a TV camera is used to pick up an image of a predetermined image pickup area including an object to be inspected or measured, and the target area including the object is within a predetermined density range within the image pickup area. An apparatus has been proposed in which the area and contour of a target can be obtained from an image by extracting pixels. In addition, in this type of device, when color information is used, the amount of information increases, and inspection or measurement can be performed accurately. Therefore, an image pickup device that can output color signals of a plurality of reference colors is required. It is considered to be used.

That is, as shown in FIG. 5, a color image processing apparatus using color information uses incident light from a predetermined image pickup area as color signals of a plurality of reference colors (generally, RGB signals are used as color signals). In the following description, the color signal is assumed to be an RGB signal, and the color signal output from the image pickup apparatus 1 is input to the video signal processing unit 11 and amplified. After such processing is performed, it is input to the A / D conversion unit 12 and converted into a digital signal. On the other hand, the target area D ₁ including the target S is
Since it is set in a part of the imaging region D ₀ as shown in FIG. 6, only the pixels in the target region D ₁ need to be extracted from the signal output from the A / D conversion unit 12. So A /
The output signal of the D conversion unit 12 is input to the comparison unit 21, and only the pixels of the target area D ₁ designated by the target area designation unit 22 are extracted. Specifically, by inputting a synchronization signal in synchronization with pixel scanning from the video signal processing section 11 to the target area designating section 22, the output signal of the A / D converting section 12 in the target area designating section 22 becomes the imaging area D. It is possible to know which pixel of ₀ corresponds to the comparison unit 21.
Then, only the pixels of the predetermined target area D ₁ can be extracted.

Further, the comparing section 21 compares the density range defined by the threshold setting section 24 based on the extraction density set by the extraction density setting section 23 with the density of the pixel in the target area D _1. By doing so, pixels having a density within the above density range are extracted from the target area D ₁ . here,
The extraction density setting unit 23 and the threshold setting unit 24 are composed of a memory. Further, the density comparison is performed for each reference color. For example, in the A / D conversion unit 12, RGB
If each of the reference colors is converted into an 8-bit digital signal, the density can be obtained in 256 gradations of 0 to 255. Therefore, the density ranges of the RGB reference colors are 50 to 100 and 100, respectively. ~ 150, 200 ~
If 250 or the like is set in the extraction density setting unit 23, the value is registered in the threshold setting unit 24 and compared with the density of the pixel of each reference color in the comparison unit 21.

The configuration of FIG. 5 is for obtaining the area of the target S, the number of pixels extracted in the comparison unit 21 is counted by the counter 41, and the measurement processing unit 42 calculates the correction of the magnification of the image pickup apparatus 1 and the like. Then, the area of the target S is obtained. The output of the A / D conversion unit 12 is converted into an analog video signal through the D / A conversion unit 43 and input to a monitor device 44 such as a CRT so that an image of an area imaged by the imaging device 1 can be visually recognized. Is done.

[0006]

By the way, in the above-mentioned configuration, when an external condition changes due to a change in the brightness of the illumination device that illuminates the target S, the color signal of the color signal is changed even if the target S does not change. Since the level changes, there arises a problem that the pixel corresponding to the target S of interest cannot be accurately extracted. If it is attempted to keep the external condition constant in order to avoid such a problem, the surrounding environment in which the target S is placed is controlled, so that the device becomes large in size and the cost becomes high, and It is very difficult to control completely.

An object of the present invention is to solve the above problems, and an object of the present invention is to provide a color image processing apparatus capable of accurately extracting a target pixel even if a condition change due to an external factor occurs. It is a thing.

[0008]

In order to achieve the above object, the present invention provides an image pickup means for converting incident light from a predetermined image pickup area into color signals of a plurality of reference colors, and a part of the image pickup area. In a color image processing apparatus including a pixel extraction unit that extracts pixels in a predetermined density range set for each color signal output from the image pickup unit with respect to a predetermined target region, a predetermined value set in a part of the image pickup region. Density correction means for generating a density control signal based on an error of the density of a pixel for each reference color with respect to a predetermined reference density for the monitor area,
It is characterized by further comprising light amount control means for changing the density of the pixel of the image pickup area for each reference color in a direction to reduce the error between the density of each pixel of the monitor area and the reference density by the density control signal.

The image pickup means includes a color separation means for optically separating the incident light into each reference color and an image pickup element for converting each incident light of each reference color separated by the color separation means into a color signal. The light quantity control means limits the transmitted light quantity according to the density control signal for each light beam arranged between the color separation means and the image pickup device of each reference color and separated by the color separation means. desirable.

Alternatively, the image pickup means optically combines the color separation means for optically separating the incident light into the respective reference colors and the light rays of the respective reference colors separated by the color separation means so as to obtain the original incident light. A color synthesizing unit for reproducing the color of the reference light and an image sensor for outputting a color signal of each reference color from the incident light synthesized by the color synthesizing unit. The amount of transmitted light may be limited in accordance with the density control signal for the light rays of the respective reference colors that are provided and separated by the color separation means.

[0011]

According to the above construction, the density of the pixel for each color signal is calculated for a predetermined monitor area set in a part of the image pickup area and compared with a predetermined reference density, and the density of the pixel in the monitor area is compared with the reference density. A density control signal is generated based on the error. Based on this density control signal, the light amount control means changes the density of the pixel in the imaging area for each reference color in the direction of reducing the error between the density of each pixel in the monitor area and the reference density. Even if the condition changes, the light amount control means can absorb the change in the condition, and the color signal of almost the same condition can be input to the pixel extraction means. As a result, the measurement accuracy is improved, and the target pixel can be accurately extracted without being affected by external conditions, and the cost is less increased than the conventional configuration, and the equipment is also reduced. It does not grow in size. In addition, when adjusting the density of the pixels in the imaging area in the direction of reducing the error between the density of the pixels in the monitor area and the reference density, the density is adjusted for each reference color, so that Even if a color change occurs, the color correction is performed, and the target pixel can be accurately extracted. In particular, the illuminance change and the color change are likely to occur in a place where the ambient light influences, but the above-described configuration can suppress the influence of the ambient light and extract pixels accurately.

The image pickup means has a color separation means for optically separating the incident light into respective colors and an image pickup element for converting the incident light of each color separated by the color separation means into a color signal, and the color separation means The light quantity control means is provided between the image pickup element of each color and each color separated by the color separation means to limit the amount of transmitted light according to the density control signal. This is a desirable configuration in the case of having the image sensor of.

Further, the image pickup means includes a color separation means for optically separating the incident light into respective colors, and a color combination means for reproducing the original incident light by combining the light rays of the respective colors separated by the color separation means. An image pickup device for outputting color signals of respective colors from the incident light combined by the color combining means, and a light amount control means disposed between the color separating means and the color combining means to separate the light by the color separating means. A configuration in which the amount of transmitted light for each color light beam is limited according to the density control signal is a desirable configuration when the color signal of each reference color is output from one image sensor.

[0014]

EXAMPLE 1 A block diagram of this example is shown in FIG. In FIG. 1, parts having the same functions as those of the conventional configuration shown in FIG. 5 are designated by the same reference numerals. The main difference between the present embodiment and the conventional configuration is a monitor area D of one pixel or more provided separately from the target area D ₁ in the imaging area D _0.
2 (see FIG. 3), a density correction means for generating a density control signal based on the density of the pixel is added, and the image pickup apparatus 1
The point is that the light quantity control unit 2 as a light quantity control means is built in.

That is, similarly to the conventional configuration, the color signals of the three reference colors of RGB output from the image pickup device 1 which is the image pickup means are input to the video signal processing section 11 and processed such as amplification and extraction of a synchronization signal. After being subjected to the A / D conversion unit 12
Entered in. The output of the A / D conversion unit 12 is input to the comparison unit 21, and the comparison unit 21 extracts the pixels of the target area D ₁ designated by the target area designation unit 22 from the extraction density setting unit 23.
And a density comparison with a predetermined density range set by the threshold setting unit 24 to determine that the pixel is within the target area D ₁ .
A pixel that satisfies the condition that the density is within the density range is extracted. That is, the comparison unit 21, the target area designating unit 22, the extraction density setting unit 23, and the threshold setting unit 24 constitute a pixel extracting unit. The counter 41 counts the number of pixels satisfying the above conditions, and the measurement processing unit 42 corrects the magnification of the image pickup apparatus 1 to obtain the result of the inspection or measurement. The results of the inspection and measurement are managed by the microcomputer 45. Furthermore, the output of the A / D conversion unit 12 is converted into an analog signal by the D / A conversion unit 43, and the image obtained by the imaging device 1 is displayed by the monitor device 44 such as a CRT.

The light quantity control unit 2 is built in the housing 10 of the image pickup apparatus 1 as shown in FIG. Imaging device 1
Is two dichroic mirrors 15a and 15b as color separation means for color-separating the incident light passing through the imaging lens 14.
And two total reflection mirrors 16a and 16b. Two
The dichroic mirrors 15a and 15b are arranged on the optical axis of the imaging lens 14 in a form inclined by 45 degrees with respect to the optical axis. One of the dichroic mirrors 15a reflects the red light and transmits the light of the other area. The total reflection mirror 16a re-reflects the red light so that the red light is substantially parallel to the optical axis of the imaging lens 14. Lead in the direction. The other dichroic mirror 15b reflects only the blue light of the light transmitted through the dichroic mirror 15a, and the blue light is re-reflected by the total reflection mirror 16b and is substantially parallel to the optical axis of the imaging lens 14. Be guided in the direction. Therefore, the green light transmitted through the dichroic mirror 15b, the red light reflected by the total reflection mirror 15a, and the blue light reflected by the total reflection mirror 15b are substantially parallel to each other, and the individual image pickup devices 17a and 17 are provided.
b, 17c (CCD, vidicon, etc.) are introduced and converted into color signals of different reference colors. Light quantity control unit 2
The respective light amount control elements 2a, 2b, 2c constituting the above are arranged in front of the respective image pickup elements 17a, 17b, 17c. As the light amount control elements 2a, 2b, 2c, those which control the opening / closing amount of a mechanical diaphragm by an electric signal and those which change the transmitted light amount of the liquid crystal panel according to the applied voltage are used. Here, the total reflection mirrors 16a and 16b may be replaced with prisms.

By the way, the density correction means includes the monitor area D ₂ among the color signals output from the video signal processing section 11.
By extracting pixels of a portion corresponding to an A / D converter 31 for converting into a digital signal, based on the output value of the A / D converter 31 to the illuminance of the concentration (i.e. the subject S of the pixel of the imaging region D ₀ (Corresponding) is detected by the density detection unit 32, the correction amount calculation unit 34 for obtaining an error of the density obtained by the density detection unit 32 with respect to the reference concentration set in the reference concentration setting unit 33, The control circuit unit 35 adjusts the light amount control unit 2 based on the obtained density error. Here, the reference density setting unit 33 sets the reference density for each reference color, and the correction amount calculation unit 34 obtains the correction amount for each reference color. Further, the density detection unit 32 obtains a moving average every time one frame of image is captured by using the density of the monitor area D ₂ in the frame (screen) input in the past. For example, a moving average of 16 frames may be calculated. The number of samples for which the moving average is calculated is not limited, and 1 instead of the moving average is used.
Other values such as a value for each frame may be used. The reference density setting unit 33 is a memory, and the reference density can be given from the outside. Further, a reference object is picked up in the monitor area D ₂ , and it is preferable that this object is achromatic, so an object such as gray is selected. Here, the timing for performing feedback control of the light quantity control unit 2 is given by a timing signal from the outside. Therefore, the light quantity control unit 2 is controlled only when adjustment is necessary, or the light quantity control unit 2 is controlled as described above. You can

As described above, the density correction means controls the light amount control section 2 via the control circuit section 35 based on the error between the density of the pixel in the monitor area D ₂ and the reference density. At this time, the light amount control unit 2 is feedback-controlled so that the above error is reduced, and as a result, the detection condition of the color signal input to the comparison unit 21 is kept substantially constant regardless of the change in the illuminance of the target S. It is possible. Here, in the feedback control, the transfer function of the density correction unit is set so that the output value of the density detection unit 32 converges within an allowable range with respect to the reference density during a repetition cycle of about 1 to several times. It is desirable to do. Further, in order to prevent the adjustment amount of the light amount control unit 2 from deviating from the permissible range during operation (that is, not to become unadjustable), the adjustment amount of the light amount control unit 2 is set in the middle of the permissible range at the start of the operation. The setting is made so that both the increase and decrease of the light amount to the image pickup devices 17a, 17b, 17c can be controlled.

(Embodiment 2) This embodiment is different from Embodiment 1 in the structure of the image pickup apparatus 1. That is, as shown in FIG. 4, as the image pickup device 17, one that can output color signals of three reference colors is used. Therefore,
The color separation means having the same configuration as that of the first embodiment separates the color signals of the respective reference colors, and the transmitted light quantity is controlled for each reference color by the light quantity control elements 2a, 2b, 2c, and then the color composition means is used to separate the colors. The image is input to the image pickup device 17 after the combination. The color combining means includes two dichroic mirrors 18a and 18b and two total reflection mirrors 19a and 19b.
and b. That is, the dichroic mirrors 18a and 18b are arranged so as to form an angle of 45 degrees on a straight line connecting the light amount control element 2b that controls the amount of transmitted green light and the image pickup element 17, and are close to the light amount control element 2b. The dichroic mirror 18a reflects red light, and the dichroic mirror 18b near the image sensor 17 reflects blue light. Therefore, the green light is incident on the image sensor 17 after passing through the light amount control element 2b. The red light is reflected by the total reflection mirror 19a, then by the dichroic mirror 18a, and then by the dichroic mirror 18b.
And enters the image sensor 17. After the blue light is reflected by the total reflection mirror 19b, it is reflected by the dichroic mirror 18b and enters the image sensor 17. In this way, the red light, the green light, and the blue light are combined and incident on the image sensor 17. Since other configurations are the same as those in the first embodiment, description thereof will be omitted.

In each of the above embodiments, the light quantity control unit 2 provided in the image pickup apparatus 1 is used to optically control the transmitted light quantity. However, the density of the color signal level output from the image pickup apparatus 1 is controlled. Similar results can be obtained by controlling with a signal.

[0021]

As described above, the present invention obtains the pixel density for each color signal in a predetermined monitor area set in a part of the image pickup area and compares it with a predetermined reference density to obtain the pixel density in the monitor area. The density control signal is generated on the basis of the error with respect to the reference density, and the light amount control means, based on the density control signal, reduces the error between the density of each pixel in the monitor area and the reference density. Since the density is changed for each reference color, even if an external condition changes, the light amount control means can absorb the change in the condition, and the pixel extraction means should be input with a color signal under substantially the same condition. It has the advantage that As a result, the measurement accuracy is improved, and the target pixel can be accurately extracted without being affected by external conditions. In addition, the cost can be reduced when compared with the case where the illumination device controls the illuminance. There is an advantage that the increase of the amount is small and the equipment is not enlarged. In addition, since the density adjustment is performed for each reference color when adjusting the density of the pixels in the image pickup area in the direction of reducing the error between the density of the pixels in the monitor area and the reference density,
Even in the case where the color of the light emitted to the object is changed, the color correction is performed, and the target pixel can be accurately extracted. In particular, the illuminance change and the color change are likely to occur in a place where the ambient light influences, but the above-described configuration has an effect that the influence of the ambient light can be suppressed and pixels can be accurately extracted.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment.

FIG. 2 is a schematic configuration diagram of an image pickup apparatus used in the first embodiment.

FIG. 3 is an explanatory diagram showing an imaging area, a target area, and a monitor area in the embodiment.

FIG. 4 is a schematic configuration diagram of an imaging device used in a second embodiment.

FIG. 5 is a block diagram showing a conventional example.

FIG. 6 is an explanatory diagram showing an imaging region and a target region in a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Imaging device 2 Light intensity control unit 2a Light intensity control element 2b Light intensity control element 2c Light intensity control element 15a Dichroic mirror 15b Dichroic mirror 16a Total reflection mirror 16b Total reflection mirror 17 Imaging device 17a Imaging device 17b Imaging device 17c Imaging device 18a Dichroic mirror 18b Dichroic Mirror 19a Total reflection mirror 19b Total reflection mirror 21 Comparison unit 22 Target area designation unit 23 Extraction density setting unit 24 Threshold setting unit 32 Density detection unit 33 Reference density setting unit 34 Correction amount calculation unit 35 Control circuit unit

Claims (3)

[Claims] 1. An image pickup unit for converting incident light from a predetermined image pickup region into color signals of a plurality of reference colors, and each color signal outputted from the image pickup unit for a predetermined target region which is a part of the image pickup region. In a color image processing apparatus including a pixel extraction unit that extracts pixels in a set predetermined density range, a predetermined reference density of pixel density for each reference color for a predetermined monitor area set as a part of an imaging area Density correction means for generating a density control signal based on an error with respect to
Color image processing comprising: a light amount control means for changing the density of pixels in the image pickup area for each reference color in a direction to reduce the error between the density of each pixel in the monitor area and the reference density by the density control signal. apparatus. 2. The image pickup means includes color separation means for optically separating incident light into respective reference colors, and an image pickup element for converting incident light of each reference color separated by the color separation means into color signals. The light quantity control means is characterized in that the light quantity control means limits the transmitted light quantity according to the density control signal for each light beam which is arranged between the color separation means and the image pickup device of each reference color and separated by the color separation means. The color image processing apparatus according to claim 1. 3. The image pickup means optically combines the color separation means for optically separating the incident light into each reference color and the light rays of each reference color separated by the color separation means to obtain the original incident light. A color synthesizing unit for reproducing and an image sensor for outputting a color signal of each reference color from the incident light synthesized by the color synthesizing unit are provided, and the light amount control unit is disposed between the color separating unit and the color synthesizing unit. 2. The color image processing apparatus according to claim 1, wherein the amount of transmitted light of the light rays of each reference color separated by the color separation means is limited according to the density control signal.